U.S. patent application number 10/012135 was filed with the patent office on 2004-06-03 for vstol vehicle.
Invention is credited to Mao, Youbin.
Application Number | 20040104303 10/012135 |
Document ID | / |
Family ID | 32391579 |
Filed Date | 2004-06-03 |
United States Patent
Application |
20040104303 |
Kind Code |
A1 |
Mao, Youbin |
June 3, 2004 |
VSTOL VEHICLE
Abstract
A VSTOL vehicle including a fuselage with two pairs of ducted
rotors fully enclosed fore and aft of the fuselage respectively.
The fuselage is aerodynamically shaped to generate lift in forward
flight. All four ducts are configured such that their center axes
are substantially parallel to each other, and at an angle tilted
sufficiently forward from the vertical axis of the fuselage. Each
ducted rotor is powered by one engine inside the duct behind the
rotor. All four rotors and engine shafts rotates counterclockwise,
generating substantial angular momentum to stabilize the vehicle
through the gyroscopic effect. Variable-shape inlets of the ducted
rotors and vector thrusting of the airflow out of the ducted rotors
combine to provide efficient power and control during all phases of
flight. The vehicle is configured to meet motor vehicle
requirements to drive on streets.
Inventors: |
Mao, Youbin; (Pasadena,
CA) |
Correspondence
Address: |
YOUBIN MAO
430 N. HOLLISTON AVENUE
#210
PASADENA
CA
91106
US
|
Family ID: |
32391579 |
Appl. No.: |
10/012135 |
Filed: |
November 29, 2001 |
Current U.S.
Class: |
244/12.5 |
Current CPC
Class: |
B64C 37/00 20130101;
B64C 29/0025 20130101 |
Class at
Publication: |
244/012.5 |
International
Class: |
B64C 029/00 |
Claims
I claim:
1. A VSTOL vehicle comprising: a fuselage shaped to develop
aerodynamic lift in a horizontal flight; a plurality of ducts,
either fully enclosed inside said fuselage, or partially or fully
outside said fuselage and rigidly connected to said fuselage, whose
center axes are at various fixed angles between said vehicle's
vertical and longitudinal axes, each said duct having inside a
rotor which rotates about the longitudinal axis of the duct to
generate independent streams of airflow for propelling and
stabilizing said vehicle, each said duct has a total axial length,
as measured from the opening of the duct to its aft end where air
flow exits, of at least more than half the diameter of the rotor
inside said duct. a plurality of power plants and transmission
means for conveying the rotational energy from said power plants to
the said rotors; control means for controlling the thrusts
generated by each said ducted rotor assembly to rotate and move
said vehicle in any direction.
2. A VSTOL vehicle as in claim 1 further comprising means for
generating and maintaining sufficiently high level of angular
momentum to stabilize said vehicle through the gyroscopic
effect.
3. A VSTOL vehicle as in claim 1 wherein said rotors and said power
plants are designed to store sufficiently high level of kinetic
energy to be utilized during takeoff and emergency landing.
4. A VSTOL vehicle as in claim 1 further comprising a plurality of
wheels allowing said vehicle to drive on land and transmission
means for conveying rotational power from said power plants to said
wheels.
5. A VSTOL vehicle as in claim 1 further comprising a plurality of
wings retractable inside said fuselage, capable of generating
upward lift during forward flight.
6. A VSTOL vehicle as in claim 1 wherein each ducted rotor assembly
further comprises a plurality of stators behind the blades of the
rotor, wherein said stators are designed to sufficiently straighten
the airflow out of the rotor blades, converting rotational energy
in the airflow to kinetic energy along the longitudinal axis of the
duct.
7. A VSTOL vehicle as in claim 1 wherein the shape of the inlet of
each said ducted rotor assembly is variable depending on said
vehicle's flight conditions, between one position during takeoff
and hover allowing more air to be drawn into the duct, and a second
position during forward flight preventing or reducing air
separation inside the duct wall.
8. A VSTOL vehicle as in claim 1 wherein each said ducted rotor
assembly further comprises an airflow directing vane system located
at the aft end of the ducted rotor assembly and movable to redirect
partially or all air stream toward any horizontal direction.
9. A VSTOL vehicle as in claim 1 wherein the shape of the side and
bottom of said vehicle is designed to utilize the ground effect
during takeoff, landing and hover mode near ground.
10. A VSTOL vehicle as in claim 1 wherein the shape and weight of
said vehicle is designed to float on water, allowing takeoff and
landing on water surface.
11. A VSTOL vehicle comprising: a fuselage shaped to develop
aerodynamic lift in a horizontal flight; two pairs of ducts, fully
enclosed fore and aft of said fuselage respectively, whose center
axes are at fixed angles between said vehicle's vertical and
longitudinal axes, each said duct having inside a rotor which
rotates about the longitudinal axis of the duct to generate
independent streams of airflow for propelling and stabilizing said
vehicle, each said duct has a total axial length, as measured from
the opening of the duct to its aft end where air flow exits, of at
least more than half the diameter of the rotor inside said duct. a
plurality of power plants and transmission means for conveying the
rotational energy from said power plants to the said rotors;
control means for controlling the thrusts generated by each said
ducted rotor assembly to rotate and move said vehicle in any
direction.
12. A VSTOL vehicle as in claim 11 further comprising means for
generating and maintaining sufficiently high level of angular
momentum to stabilize said vehicle through the gyroscopic
effect.
13. A VSTOL vehicle as in claim 11 wherein said rotors and said
power plants are designed to store sufficiently high level of
kinetic energy to be utilized during takeoff and emergency
landing.
14. A VSTOL vehicle as in claim 11 further comprising a plurality
of wheels allowing said vehicle to drive on land and transmission
means for conveying rotational power from said power plants to said
wheels.
15. A VSTOL vehicle as in claim 11 further comprising a plurality
of wings retractable inside said fuselage, capable of generating
upward lift during forward flight.
16. A VSTOL vehicle as in claim 11 wherein each ducted rotor
assembly further comprises a plurality of stators behind the blades
of the rotor, wherein said stators are designed to sufficiently
straighten the airflow out of the rotor blades, converting
rotational energy in the airflow to kinetic energy along the
longitudinal axis of the duct.
17. A VSTOL vehicle as in claim 11 wherein the shape of the inlet
of each said ducted rotor assembly is variable depending on said
vehicle's flight conditions, between one position during takeoff
and hover allowing more air to be drawn into the duct, and a second
position during forward flight preventing or reducing air
separation inside the duct wall.
18. A VSTOL vehicle as in claim 11 wherein each said ducted rotor
assembly further comprises an airflow directing vane system located
at the aft end of the ducted rotor assembly and movable to redirect
partially or all air stream toward any horizontal direction.
19. A VSTOL vehicle as in claim 11 wherein the shape of the side
and bottom of said vehicle is designed to utilize the ground effect
during takeoff, landing and hover mode near ground.
20. A VSTOL vehicle as in claim 11 wherein the shape and weight of
said vehicle is designed to float on water, allowing takeoff and
landing on water surface.
Description
FEDERALLY SPONSORED RESEARCH
[0001] Not Applicable
SEQUENCE LISTING OR PROGRAM
[0002] Not Applicable
BACKGROUND--FIELD OF INVENTION
[0003] This invention relates generally to vertical or short
takeoff and landing (VSTOL) vehicle, specifically to an improved
VSTOL vehicle that is stable and capable of high speed cruise with
ducted rotors wherein the ducts remain stationary and at an angle
between the vertical and longitudinal axes of the vehicle, and the
thrusts from the ducted rotors are adjustable and vectored.
BACKGROUND--DESCRPTION OF PRIOR ART
[0004] Ducted rotors, also known as ducted fans, are more efficient
and quieter than exposed propellers of the same diameters. They are
also safer than exposed propellers on the ground.
[0005] Several designs have involved ducted rotors to achieve VSTOL
with high-speed cruise capability. The designs have included
separate fans for vertical and horizontal thrust (see U.S. Pat. No.
5,890,441); ducted fans mounted in the fixed wings which rotate
from horizontal to vertical (see U.S. Pat. No. 3,335,977). These
designs suffer from inefficient redundancy, or heavy and complex
mechanism that are prone to failure, particularly during transition
from hover to flight and vice versa.
[0006] A more recent design has four ducted fans fixed on both
sides of the fuselage and mounted parallel to the longitudinal axis
of the fuselage, and rely on the vanes at the aft part of each
ducted fan to redirect airflow for vertical takeoff and landing
(see U.S. Pat. No. 5,115,996). This design was intended to achieve
efficient high-speed cruise. On closer look, however, such
compromise makes vertical take-off inefficient as ninety degree
thrust vectoring during takeoff causes significant power loss just
when the thrust and power are most needed. Furthermore, bigger
ducted fans and more powerful engines are required to push enough
airflow to compensate for the power loss due to thrust vectoring
during vertical takeoff. Yet bigger fans produce more drag at
high-speed cruise, which was what the design was supposed to
achieve. Four big fans drawing in air from the front still
represents significant safety hazard on the ground. Noise can
easily escape from both the front and aft ends of the ducts.
Stability control during transition from hovering to forward flight
can also be very challenging.
[0007] Yet another recent design example is the DuoTrek by
Millennium Jet Inc., which has four shallow (depth of the duct
substantially smaller than the rotor diameter) ducted fans mounted
horizontally on both sides of the fuselage. The design has only a
very moderate top speed, as the horizontally mounted and shallow
ducted fans are not efficient for high-speed cruise. Noise level
will also be necessarily high as the ducts are too shallow to
provide much shield.
OBJECTS AND ADVANTAGES
[0008] Therefore several objects and advantages of the present
invention are:
[0009] (a) to provide a VSTOL design that presents a better
compromise between the conflicting requirements of vertical take
off and high speed cruise.
[0010] (b) to provide a VSTOL design that is inherently more stable
and easier to control during all phases of flight, particularly
during the transition between hover and forward flight which has
been particularly challenging to previous designs.
[0011] (c) to provide a VSTOL design that takes full advantage of
the potential benefits of ducted rotors;
[0012] (d) to provide a VSTOL design that is more efficient in
reducing drag and power requirements during all phases of
flight.
[0013] (e) to provide a VSTOL design that is safe with multiple
measures for emergency landing.
[0014] (f) to provide a VSTOL design that is quiet.
[0015] (g) to provide a VSTOL design that is compact, versatile and
capable of multiple use, including meeting motor vehicle
requirements to drive on local streets and highways;
[0016] (h) to provide a VSTOL design that is capable of flying
close to ground much as a hovercraft to take advantage of the
ground effect.
[0017] Still further objects and advantages will become apparent
from a consideration of the ensuing description and drawings.
SUMMARY
[0018] In accordance with the present invention, a preferred
embodiment includes a fuselage with two pairs of ducted rotors
fully enclosed fore and aft of the fuselage respectively, and two
vertical stabilizers attached to the fuselage. The fuselage is
configured to generate aerodynamic lift in forward flight. All four
ducts are configured such that their center axes are substantially
parallel to each other, and at an angle tilted sufficiently forward
from the vertical axis of the fuselage. Each ducted rotor is
powered by one engine inside the duct behind the rotor.
[0019] In the preferred embodiment of the present invention, all
four rotors and engine shafts rotate counterclockwise, generating
substantial angular momentum to stabilize the vehicle through the
gyroscopic effect. Variable-shape inlets of the ducted rotors and
vector thrusting of the airflow out of the ducted rotors combine to
provide efficient power and control during vertical flight.
DRAWINGS
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In the drawings, closely related figures have the same
number but diferent alphabetic suffixes.
[0021] FIG. 1 is a perspective view of a VSTOL vehicle in preferred
embodiment in accordance with the present invention.
[0022] FIG. 2a is a side cross-section view showing relative
location and angle from horizontal of the fuselage and the ducted
rotor assemblies during typical horizontal flight.
[0023] FIG. 2b is a side cross-section view showing relative
location and angle of the fuselage and the ducted rotor assemblies
in reference to the ground during initial vertical takeoff and in
reference to the horizon during vertical flight of the vehicle.
[0024] FIGS. 3a-3c illustrate the control of the magnitude and
direction of the thrust of one ducted rotor assembly through the
exit vanes.
[0025] Reference Numerals In Drawings
[0026] 10 fuselage 12 front ducted rotor assembly
[0027] 14 rear ducted rotor assembly
[0028] 22 vertical stabilizer 24 rudder
[0029] 26 horizontal stabilizer 28 elevator
[0030] 32 retractable wing
[0031] 36 front wheel 37 rear wheel
[0032] 41 engine
[0033] 42 rotor 44 stators
[0034] 45 inlet louvers
[0035] 47 exit vane 48 airflow flap
[0036] 49 airflow guide
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0037] FIG. 1 shows a perspective view of a VSTOL vehicle in the
preferred embodiment of the present invention. The preferred
embodiment includes an elongated fuselage 10 shaped to produce lift
during forward flight, with four ducted rotor assemblies 12L, 12R,
14L, 14R fully enclosed inside the fuselage. Two of the ducted
rotor assemblies 12L and 12R are located in the fore of fuselage 10
and forward of the center of gravity of the fuselage, and the other
two ducted rotor assemblies 14L and 14R are located in the aft of
the fuselage 10 rearward of the center of gravity of the fuselage.
Two vertical stabilizers 22L and 22R are respectively attached to
and rise from the left and right edges of the rear end of the
fuselage 10. Two rudders 24L and 24R are respectively mounted to
the rear edges of the two vertical stabilizers 22L and 22R. One
horizontal stabilizer 26 is bridged between the top edges of the
two vertical stabilizers 22L and 22R, with elevators 28L and 28R
mounted to the left and right sides of the rear edge of the
horizontal stabilizer 26. A pair of retractable wings 32L and 32R
(shown in open position) is hidden underneath the cockpit when not
in use.
[0038] As illustrated in FIG. 2a, in the horizontal flight mode,
the inlets of the ducts are already at an angle to the incoming air
stream. In the preferred embodiment, the ducts are installed such
that their center axes are parallel to each other and at an angle
about 30 degrees forward of the vertical axis of the fuselage. The
exiting air is redirected to almost fully horizontal through the
exit vanes 47 in each ducted rotor assembly.
[0039] FIG. 2b shows the operation of the vehicle in the vertical
takeoff or vertical flight mode. The vehicle initially rests on
front and rear wheels 36 and 37 (Shown in FIG. 1). To start the
vertical takeoff, the exit vanes 47 in the front pair of ducted
rotor assemblies 12L and 12R are configured to produce substantial
thrust, which lifts the front portion of the vehicle up and rotates
around the rear wheels 37, until the longitudinal axis of the
fuselage points about 30 degree above horizon, and all four ducted
rotor assemblies thrust the airflow straight downward. With all
four ducted rotor assemblies in full power mode, the vehicle lifts
off.
[0040] The detailed structure of a ducted rotor assembly can also
be seen in FIGS. 2a and 2b. The present invention requires a
"deeply" ducted rotor configuration such that the axial length of
the duct is at least half of the diameter of the rotor. Some
previous designs employ only a shallow shroud around the rotor.
Such configuration is commonly referred to as "shrouded fan" in the
art. The more elongated duct in the present invention would allow
the incoming air more time to accelerate smoothly and become more
evenly distributed when it reaches the rotor, which results in
efficient operations at a wide range of cruise speeds.
[0041] The cross section of the duct has a rectangular shape at the
inlet, and gradually turns into circular shape at the rotor. After
that it gradually turns rectangular again for effective thrust
control by the exit vanes 47. The cross section area of the duct
should be gradually and smoothly reduced from the inlet to the
rotor, so the inflow air can be smoothly accelerated toward the
rotor without separation.
[0042] The engine 41 is of Wenkel rotary type for the following
reasons: A rotary engine is more reliable because it has far fewer
moving parts than a piston engine. It can also be made more compact
than piston engines of the same power. Unlike a piston that rapidly
and violently changes direction, the rotor in a rotary engine spins
in the same direction, resulting in smoother and quieter operation,
as well as more angular momentum for the attitude stability control
in the present invention. Each rotor assembly has a number of rotor
blades 42, and a number of stators 44 behind the rotor blades. The
tips of the rotor blades must be very close to the duct wall for
best efficiency. The number of stators is different from the number
of rotor blades to reduce vibration. The rotor blades are built
with heavier material and strengthened at the tips to maximize
angular momentum generated as well as to store sufficient kinetic
energy to sustain effective thrust for about three minutes during
emergency landing in case of engine failure. The heavier blades
also lead to smoother rotation and reduced noise level. The stators
have cross sections of airfoil shape and are angled to
substantially straighten the airflow that is slightly swirling
coming out of the rotor blades. The stators not only convert the
swirling energy of the airflow into straight kinetic energy that
produces thrust, they also cancel out the torque exerted on the
rotor blades by the air.
[0043] The inlet has a number of movable louvers 45. The duct exit
comprises of three movable exit vanes--front vane 47F, middle vane
47M, and the rear vane 47R, and airflow flap 48 and guide 49.
[0044] As shown in FIG. 2a, in the forward flight mode, the inlet
louvers 45 tilt forward to guide the incoming air toward the rotor
42. Properly angled, the inlet louvers can minimize the airflow
separation around the inlet area during forward flight. The exit
vanes 47 are fully extended forward with the airflow flap 48 open
to direct all airflow backward.
[0045] Refer to FIG. 2b for the operation of the ducted rotor
assembly in vertical takeoff and vertical flight mode. The inlet
louvers 45 are fully opened to draw in more air, which improves the
static thrust. Even the surface area around the inlet now has a
lower static air pressure as the air moves toward the inlet, an
additional benefit that is not realized by designs with exposed
ducts or ducts installed horizontally. The inlet louvers 45 are
lined parallel to the duct wall to guide the air straight down
toward the rotor 42. The airflow flap 48 is closed. The exit vanes
47 are positioned substantially parallel to the duct wall to guide
the airflow straight down. Note that some airflow is intentionally
directed towards the front and the rear by 47F and 47R in order to
achieve thrust magnitude and direction control as shown in FIGS.
3a-3c.
[0046] During the vertical takeoff and vertical flight mode, the
control surfaces of the rudders and elevators are ineffective. In
the preferred embodiment, all rotor blades have fixed pitch for
simplicity and reliability. And the engine power usually cannot be
adjusted quickly and dependably for the purpose of stability
control. It leaves the exit vanes as the only effective means of
thrust control during vertical takeoff and vertical flight.
[0047] As shown in FIGS. 3a-3c, the thrust magnitude and direction
of a ducted rotor assembly can be effectively controlled by varying
the positions of the exit vanes 47F, 47M and 47R.
[0048] FIG. 3a illustrates the exit vanes in the neutral position,
with 47F and 47R partially redirecting airflow to the front and the
back. As shown in FIG. 3b, when 47F and 47R are turned to direct
even more air to the front and the back, the net vertical thrust is
reduced. To increase the net vertical thrust, 47F and 47R should be
turned toward vertical position. FIG. 3c shows 47F, 47M and 47R all
turn to direct air partially to the back to product a thrust
forward. Note that the angles in FIGS. 3a-3c are exaggerated for
better illustrations.
[0049] Noting that the present invention utilizes the high angular
momentum generated by the rotor assemblies to achieve high
stability through the gyroscopic effect, the pitch and roll
controls of the vehicle are more similar to those of a helicopter
than for a fixed wing aircraft. For example, to pitch forward, a
net torque towards the front must be applied. During vertical
takeoff and hovering, this is achieved by increasing the vertical
thrusts of the two ducted rotor assemblies on the left side (12L
and 14L) while reducing the vertical thrusts of the two ducted
rotor assemblies on the right side (12R and 14R). The roll control
is similarly achieved by using differential vertical thrusts
produced by the front pair of ducted rotor assemblies (12L and 12R)
and the rear pair of ducted rotor assemblies (14L and 14R). The yaw
control is realized by differentially thrusting forward or backward
the two ducted rotor assemblies on the left side (12L and 14L)
while thrusting in the opposite direction for the two ducted rotor
assemblies on the right side (12R and 14R). During full forward
flight, all thrusts are directed fully backward, making the
attitude control through the thrust vectoring impossible. Thus the
conventional control surfaces--the rudders 24L, 24R and the
elevators 28L and 28R, takes over the attitude control during
forward flight.
[0050] The vehicle is also capable of short take off and landing
with the conventional control.
[0051] The rotor shafts of the front pair of ducted rotor
assemblies are connected by a transmission mechanism such that if
one engine fails, the remaining engine can still power the two
rotors for safe vertical landing. The rotor shafts of the rear pair
of the ducted rotor assemblies are similarly connected.
[0052] With the retractable wing 32 opened up, the vehicle can
extend its cruise range, or stay in the air longer for aerial
surveillance. It can also fly close to the ground to take advantage
of the ground effect, with the lower sides of the vehicle and the
wings providing good air cushion.
[0053] The vehicle is designed to float on water, particularly for
emergency landing and takeoff.
[0054] Advantages
[0055] From the description above, a number of advantages of the
present invention become evident:
[0056] (a) The present invention provides an optimal compromise
between the conflicting requirements of vertical takeoff and
high-speed cruise. The required maximum engine power of a VSTOL
vehicle is determined by the power needed for vertical takeoff. The
present invention prevents power loss due to thrust vectoring
during vertical takeoff as in some previous designs. Furthermore,
the variable inlets opening up to draw in more air during vertical
takeoff leads to better lift efficiency, thus further reduces the
maximum engine power requirement.
[0057] (b) The present invention provides an efficient VSTOL
design. The reduced maximum engine power requirement leads to
reduced weight of the power system and better fuel efficiency for
cruise. Furthermore, without open propellers or exposed external
ducts, the present design is more aerodynamic with much less drag,
resulting in efficient high-speed cruise. The variable inlet design
combined with the deeply embedded rotors allows the rotors to
operate at very high efficiency in a wide range of speed. It also
opens the design for very high-speed cruise with the more powerful
turbo jet engines. A turbo engine happens to provide very high
angular momentum with the high rotation rate of its shaft.
[0058] (c) The present invention provides a stable and safe VSTOL
design. The high angular momentum generated by the rotors and the
engine shafts provides the vehicle with very high stability through
the gyroscopic effect. The high kinetic energy stored in the rotor
blades can also be used for emergency landing. The power redundancy
achieved by connecting the front and the rear pair of rotor shafts
together with a transmission mechanism provides further security
against single engine failure. In an unlikely event that one pair
of ducted rotors fails altogether, the vehicle will still be able
to fly with the remaining pair of rotors and land on a runway,
particularly with the retractable wing open and with the help of
the ground effect. And the vehicle can land on water, increasing
the chance of a safe landing. Without big wings, and with an
aerodynamic body, the vehicle is not susceptible to gust winds. A
reliable control system is implemented on triple redundancy
computers.
[0059] (d) The present invention provides a VSTOL design that is
quieter than previous designs. The fuselage provides a better sound
insulation than the nacelles of exposed ducted rotors can. The
rotary engine and the heavier rotor blades lead to smoother and
quieter operation. The deeply embedded rotors allow many active
noise suppression technologies to apply. The air is drawn from the
top of the fuselage during takeoff, rather than from the front like
some other previous designs, resulting in further reduced noise
levels.
[0060] (e) The present invention provides a VSTOL design that is
safe on the ground, without any exposed propellers or nacelles, and
without drawing in air from horizontal directions during
takeoff.
[0061] (f) The present invention provides a VSTOL design that is
compact, and can meet the motor vehicle requirements to drive on
local streets and highways without much technical difficulties. The
purpose is to allow the pilot to drive to and from a place for safe
takeoff and landing.
[0062] Additional Embodiments
[0063] There are many additional embodiments that can demonstrate a
variety of applications in accordance with the present
invention.
[0064] (a) The vehicle in the preferred embodiment has all four
rotors rotate in the counterclockwise direction to generate the
most angular momentum for stability control. The stators are
required to sufficiently straighten the airflow out of the rotor
blades. An alternative embodiment relaxes this requirement by
rotating the left front (12L) and the right rear (14R) rotors
clockwise. A net angular momentum can still be achieved by
constructing the left front (12L) and the right rear (14R) rotor
blades with lighter materials. This design generates far less
angular momentum for stability control and less kinetic energy
stored for emergency landing. The benefits include simpler stator
design and the ability to achieve yaw control through differential
rotation rate or differential pitching between the diagonal pairs
of rotors.
[0065] (b) A very simple and low cost alternative design deploys
counter-rotating rotors as in embodiment (a). Furthermore, four
rotors are identical such that they do not generate significant net
angular momentum. The variable inlets and thrust vectoring vanes
are both optional in this embodiment. The attitude control is
completely achieved through differential rotation rate or
differential pitching of the four rotors. It is a cost effective
design suitable for slower flight applications.
[0066] Conclusion, Ramifications, and Scope
[0067] Thus it can be seen that the VSTOL vehicle of the present
invention provides an efficient, stable, safe, quiet, compact,
versatile yet practical design for many potential applications such
as public transportation, search and rescue, and military
operations.
[0068] While my above description contains much specificity, these
should not be construed as limitations on the scope of the
invention, but rather as an exemplification of one preferred
embodiment thereof. Many other variations are possible. For
example:
[0069] (a) A VSTOL flying disk with three embedded ducted rotors
located 120 degree apart. The extreme symmetry in such design makes
it highly maneuverable in all direction and less susceptible to any
sudden change of the wind direction.
[0070] (b) A VSTOL aircraft with two deeply ducted rotors in the
fore and aft of the fuselage, with two open propellers horizontally
mounted on its wings to provide both yaw control as well as
additional propulsion.
[0071] Accordingly, the scope of the invention should be determined
not by the embodiments illustrated, but by the appended claims and
their legal equivalents.
* * * * *